async function async1() {
    console.log('async1 start')  
    await async2()
    console.log('async1 end')
}
async function async2() {
    console.log('async2')  //3
}
console.log('script start')  //1 
setTimeout(function () {
    console.log('setTimeout')
})
async1() // 2
new Promise(function (resolve) {
    console.log('promise1')
    resolve()
}).then(function () {
    console.log('promise2')
})
console.log('script end')

// script start
// async1 start
// async2
// promise1
// script end
// async1 end
// promise2
// setTimeout